Age Calculator
Work out an exact age in years, months and days, total days lived, and a live countdown to the next birthday — calendar accurate.
Pick both dates to see the result.
Leap years and varying month lengths are handled exactly — 29 February birthdays fall back to 1 March in non-leap years.
This tool runs entirely in your browser. Your data never leaves your device — it is not uploaded to any server.
How to use
- 1Pick the date of birth.
- 2Leave the age-at date on today, or change it to any other date.
- 3Read the exact age, total months and days, and the next-birthday countdown.
Age Calculator
Enter a date of birth and this calculator reports the exact age — years, months and days, not an approximation — plus total months and total days lived. It also counts down to the next birthday with the weekday it falls on.
The “age at date” field defaults to today and can be changed to any past or future date, which makes it easy to answer questions like “how old was she on graduation day?”.
Frequently asked questions
How is the age in years, months and days computed?
By calendar arithmetic, not an average month length: years and months are counted whole, and leftover days are measured against the actual length of the month — including leap years. Someone born on 29 February is counted a year older on 1 March in non-leap years.
Can I calculate an age at a date in the past or future?
Yes. The “age at date” box is editable, so you can compute a historical age or check how old someone will be at a future event. The birth date must not be after the age-at date.
Why does the total-days number matter?
Total days lived is the figure used for “days on earth” style milestones and for systems that store ages in days. It is computed from calendar dates in UTC so daylight-saving shifts cannot make it off by one.
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Embed this tool
Put this tool on your own site with one line — it runs entirely in the visitor's browser.
<iframe src="https://zoyku.com/en/tools/age-calculator?embed=1" width="100%" height="640" style="border:0;border-radius:16px" title="Zoyku — age-calculator" loading="lazy"></iframe>